1. Field of the Invention
The invention relates generally to an apparatus for stacking planar or substantially flat articles, and more particularly to an apparatus for successively stacking transparency frames or other substantially flat articles into a receiving shaft.
2. Description of Prior Art
In the manufacture of photographic slides, a stacking mechanism is often provided in conjunction with sorting machines for transparency frames, or with lettering machines for the frames. Generally, such stacking mechanisms are used whenever planar articles are manufactured or subjected to individual treatment, and then disposed or stacked in, for example, a magazine. In one type of prior art stacking mechanism, rubber bands follow a conveyor belt on which the planar articles or transparency frames are guided and from which they drop freely into a magazine, a stacking shaft etc. This dropping movement, however, is uncontrolled, and frequently leads to breakdowns.
In another known stacking mechanism, an arrangement has been provided to prevent the dropping movement from being carried out completely uncontrolled. The arrangement consists of guide members disposed in the area of the trajectory of the transparency frames to move the transparency frames from a horizontal position into a vertical position along a sector of a circular arc. This arrangement, too, is not wholly satisfactory, since the effect of the guiding arrangement is, among other factors, greatly dependent on the speed and the mass of the transparency frames. Whenever the speed of the transparency frames is too low, the guide members are not contacted. Whenever the speed is too high, the transparency frames rebound from (bounce off) the guide members.